Report from the Canadian Chronic Disease Surveillance System: Hypertension in Canada, 2010

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Executive Summary

Hypertension

Hypertension is a chronic condition that occurs when blood pressure is consistently high for long periods of time. Blood pressure is the pressure or force of blood against the walls of blood vessels as it circulates.

The risk of developing hypertension can be reduced by adopting a healthy lifestyle that includes regular physical activity, maintaining a healthy body weight, managing stress, limiting alcohol consumption, and eating a healthy diet low in sodium, with adequate fresh fruits and vegetables, and limited fat and simple sugars.

In most cases, hypertension has no symptoms and can only be diagnosed through proper blood pressure measurement. If left untreated, hypertension increases a person’s risk of stroke, heart attack, dementia, heart and kidney failure and other chronic diseases. However, hypertension can be controlled to lower the risk of developing these serious diseases.

Hypertension and diabetes often co-exist, along with other cardiovascular risk factors such as obesity and high levels of lipids or fats in the blood. The greater the number of cardiovascular risk factors an individual has, the higher the likelihood of having a heart attack, stroke or other serious cardiovascular disease outcome.

Canadian Chronic Disease Surveillance System (CCDSS)

The Canadian Chronic Disease Surveillance System (CCDSS) is a collaborative network of provincial and territorial surveillance systems, supported by the Public Health Agency of Canada (PHAC). It uses provincial/territorial health administrative databases including physician billing, hospitalization and resident registry databases, and was initially used to track diabetes (formerly known as the National Diabetes Surveillance System (NDSS)). In 2009, hypertension was added to the CCDSS and other chronic diseases will be added in the future.

In the CCDSS, diagnosed hypertension is defined based on a minimum requirement of at least two physician claims within a two-year period, or one inpatient hospital separation abstract listing hypertension as a diagnosis, and uses the International Classification of Diseases (ICD), 9^th or 10^th Edition hypertension codes.

Key Findings

This report features the most recent data available, fiscal year 2006/07, as well as trend data from 1998/99 onwards. Where data on both diagnosed hypertension and diabetes are presented, trend data are from 2000/01 onwards as data for diabetes were not available prior to this year. Data for Nunavut and Québec were unavailable for this report but will likely be available in future reports. Data were reported for adults aged 20 years and older.

Prevalence ¹

• Nearly 6 million Canadians aged 20 years and older ² – more than one in five adults – were living with diagnosed hypertension in 2006/07 (24.0% of women and 21.3% of men, crude prevalence).
• The age-standardized prevalence of diagnosed hypertension increased from 12.9% in 1998/99 to 19.6% in 2006/07.
• Projections indicate that if current age and sex trends continue, by 2011/12, about 7.3 million Canadians will be living with a hypertension diagnosis – an estimated increase of 25.5% since 2006/07. ²
• The age-standardized prevalence of diagnosed hypertension in Canada was highest in the Atlantic provinces and lowest in the west and north (Yukon, Northwest Territories, and British Columbia).

Incidence ¹

• In 2006/07, about 450,000 adults were newly diagnosed² with hypertension (22.1 per 1,000 population aged 20 years and older – 21.6 per 1,000 women and 22.7 per 1,000 men, crude incidence).
• Age-standardized incidence rates of diagnosed hypertension remained stable throughout the surveillance period with overall incidence rates of 26.2 per 1,000 in 1998/99 and 25.8 per 1,000 in 2006/07.
• Yukon has the highest age-standardized incidence rate of diagnosed hypertension, closely followed by Newfoundland and Labrador. The lowest rates were observed in Ontario and the Northwest Territories. In 1998, in Yukon, a large proportion of claims did not have the reason for the visit or diagnosis coded in the system. The lower number of new cases of diagnosed hypertension that were documented during the earlier years in Yukon likely had an impact on the lower prevalence of diagnosed hypertension during the years under surveillance as prevalent conditions are cumulative.

Hypertension and Diabetes ^1,3

• In 2006/07, 5.1% of Canadians (about 1 million) aged 20 years and older were living with both diagnosed diabetes and hypertension.
• 22.7% of adults with diagnosed hypertension also had diabetes.
• Adults with diagnosed hypertension were 6 times more often diagnosed with diabetes than those without hypertension.
• 62.8% of adults with diagnosed diabetes also had diagnosed hypertension.
• Adults with diagnosed diabetes were 3 times more often diagnosed with hypertension than those without diabetes.
• Age-standardized prevalence of diagnosed diabetes among adults with diagnosed hypertension increased from 10.9% in 2000/01 to 14.3% in 2006/07.

All-Cause Mortality ¹

• Between 1998/99 and 2006/07, all-cause mortality rates for adults with diagnosed hypertension have decreased from 7.3 per 1,000 to 6.7 per 1,000 among women, and from 12.2 per 1,000 to 10.2 per 1,000 among men.
• In 2006/07, all-cause mortality rates were respectively 34% and 44% higher among women and men with diagnosed hypertension than among women and men without diagnosed hypertension.
• In 2006/07, age-standardized all-cause mortality rates were about 2 times higher for adults with both diagnosed hypertension and diabetes compared to adults with diagnosed hypertension only.

CCDSS Future Plans

Future work will include reporting on diagnosed hypertension in Canada on a regular basis. Continuing work with the provinces and territories to expand the CCDSS to other chronic conditions such as heart disease and stroke will allow PHAC to track whether these outcomes of hypertension control are changing among individuals with hypertension.

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¹ Data for Nunavut and Québec were unavailable.
² Data for Nunavut were unavailable. Data for Québec were also unavailable. However, the number of cases for Québec was estimated by applying the Canadian age-specific rates for people with hypertension to the Québec population.
³ The Canadian Hypertension Education Program recommends that individuals with hypertension lower and maintain their blood pressure, through lifestyle modification and/or pharmacotherapy, below 140/90 mmHg, and among those with diabetes or chronic kidney disease below 130/80 mmHg.

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